Burner heated oil supply system



July 28, 1959 E. M. RuLsEH BURNER HEATED om SUPPLY SYSTEM Filed Jan. 18, 1956 INVENTOIL M ]alsef,

. Elf@ United. States Patent BURNER HEATED OIL SUPPLY SYSTEM Elroy M. Rulseh, Milwaukee, Wis., assignor to Cleaver- Brooks Company, a corporation of Wisconsin Application January 18, 1956, Serial No. 559,847

3 Claims. (Cl. 158-36) heating devices frequently make. use of very heavy and viscous grades of fuel oil. While `the use of such oils effects major economies in fuel costs, it gives rise to other problems, and particularly to problems in owing the fuel oil from a supply source such as a tank to the burner nozzle, and in supplying the fuel oil to the vburner nozzle at the proper temperature for atomization and efficient combustion. For example, while certain grades of fuel oil will llow easily under surrounding temperature conditions normally encountered, it is necessary that the oil be heated to a temperature suitable for insuring proper atomization and combustion at the burner nozzle. Also, other grades of oil in use today are so heavy and viscous that they will not ow through the supply lines under normal conditions and become even heavier and more sluggish in extremely cold weather so as to clog the supply lines and resist ilow to the burner nozzle, thus requiring cumbersome, expensive and time-consuming steps in clearing the lines to prepare for operation of the burner after shutdown.

Accordingly, it is a more specific object of the invention to provide a new and improved system of the type described wherein provision is made for establishing circulation of oil through the system after extended periods of burner shut-down.

Another object of the invention is to provide a new and improved system of the character described wherein provision is made for circulating heated oil through the system during temporary periods of burner shut-down so as to maintain the system in readiness for firing.

A further object is to provide, in a system of the character described, constant circulation of heated oil during firing and during shut-down to compensate for ambient temperature conditions.

Another object is to provide, in a system of the type described, circulation of a predetermined quantity of heated oil through the system and through the supply tank and to make provision for varying the quantity of oil recirculated to compensate for changing temperature conditions.

Another problem encountered in the use of systems of the type described is that of providing the proper amount of oil at the burner nozzle at the proper pressure conditions for obtaining the most efficient atomization and combustion of the fuel. Prior systems have employed complicated and delicate pumping devices which are calculated to deliver a precise volume of fluid to the burner nozzle at the proper pressure conditions. However, such pumping devices have often given rise to diticulties since proper atomization and combustion at the burner nozzle depends entirely upon the proper functioning of the pumping device which frequently varies with wear on the pump ICC and with variations in temperature and pressure conditions at the pump.

It is also an object of this invention to provide a system of the character described which is unaffected by the quantity or pressure of fuel oil supplied by the pumping device, thus permitting a number of burner units to` be connected in parallel with a single fuel supply pump.

Other objects and advantages will be readily apparent from the following detailed description taken in connection with the accompanying drawing, in which:

The drawing isla circuit diagram of a. system embodying the principles of my invention.`

While an illustrative embodiment of the invention is shown in the drawing and will be described in detail herein, the invention is susceptible of embodiment in many different forms, and it should be understood that the present disclosure is to be considered as an exemplilication of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. VThe scope of the invention will be pointed out in the appended claims. h

Referring now to the drawing, the circuit illustrated there includes a burner having a houle 10 to which air and oil under pressure are supplied for producing an atomized spray for combustion. Air under pressure is supplied to the nozzle 10 through a line 11 from a source not shown. Oil under pressure is delivered to the nozzle 10 through a line 12 from a source to be described presently. A gas pilot 13 may be provided adjacent the nozzle 10 for maintaining a pilot light for initiating combustion at the nozzle after periods of burner shut-down.

Oil is supplied to the line 12 through a modulating valve 14, which may be of the type described more fully in the co-pending application of Frederick A. Loebel et al., filed January 20, 1956, as Serial Number 560,393, and may function automatically in response to the burner demand to regulate the volume of ow to the burner nozzle 10. A line 15 connected to the outlet of the modulating valve 14 and to the line 12 is provided with a solenoid controlled valve 16 which functions either to permit communication between the modulating valve v14 and the line 12 or to block the passage of oil through the line 15. The solenoid controlled valve 16 may be automatically governed to open in response to burner demand for oil and to close automatically when there is no call for oil. The lines 12 and 15 are connected through a check valve 17 and an air conduit 18 to `an air purge system for cleaning the fuel supply lines between the solenoid valve 16 and burner nozzle 10 on shutdown of burner tiring. This air purge system is described more fully` and claimed in my co-pending application field March 24, 1955, as Serial Number 496,372, now Patent No. 2,818,110. While the line 15 connecting the modulating valve and the line 12 is shown as having a substantial length, this showing is provided merely for purposes of clarity, and in actual practice the line 15 is as short as possible in order that the air purge system will eiectively remove oil from this line on burner shut-down.

Oil under pressure is supplied to the system by means of a pump 20 having its inlet connected by a line 21 to a supply tank (not shown) and having its outlet connected to a supply line 22. The supply line is provided with a pressure relief valve 23 having its outlet connected with a return line 24 which leads to the tank. The capacity of the pump 20 in terms of pressure and volume may materially exceed the capacity of the nozzle 10 referred to above, and may be sulicient to supply a number of burners in addition to the one shown because, as explained hereinafter, the pressure at the nozzle 10 is unaffected by the pressure delivered by the pump 20. The pressure at which the relief valve 25` opens may be varied to conform with the capacity of the pump 20 and the demands of the system generally.

Oil pumped through the line 22 which does not pass through the relief valve 23 is pumped through a heater 25 for elevating the temperature of the oil and passes out of the heater through a line 26 to the modulating valve 14. The heater 25 may include an electrical heating element 27 controlled by a thermostat 28 connected in the line 26, so as to maintain the oil at the proper elevated temperature. The heater may also be supplied with steam heat through a conduit 29 leading through the heater, steam condensate being withdrawn through a line 30. The admission of steam to the heater 25 may be controlled by a steam thermostat 31 associated with the heater. The heater 25 is provided for elevating the temperature of oil pumped therethrough to maintain it in a sufficiently Huid condition to permit its iiow and/or proper atomization at the burner nozzle. The capacity of the heater employed may vary considerably depending upon the particular system and the demands made on that system. In a typical construction, the electrical element 27 may be a 5 kw. element which is capable of raising the temperature of 44 gallons per hour of #6 oil 100 F. If, additionally, 5 p.s.i. of steam is supplied through the line 29 to the heater, the combined effects will be'sufcient to raise the temperature of 75 gallons per hour of #6 oil 100 F., from 80 F. to 180 F., for example.

From the heater 25, the heated oil flows through the line 26, a filter 35 in the line 26, thence to a pressure reducing valve 36 in the line 26, and then to the modulating valve 14. The pressure of fiuid entering the pressure reducing valve 36 is determined by the pressure relief valve 23 and may be read on a pressure gauge 37 in the line 26, and remains substantially constant. The pressure reducing valve 36 may be adjusted manually to provide a predetermined constant pressure at the modulating valve 14 which may be read on a pressure gauge 38. Thus, it will be seen that the pressure relief valve andthe pressure reducing valve 36 cooperate to maintain the oil at a substantially constant pressure at the modulating valve 14 for delivery to the burner nozzle 10, regardless of the volume and pressure provided by the pump 20 and independent of the volume delivered to the burn er 10. Therefore, any number of systems such as the one` shown may be connected in parallel and supplied from a common pump and each system will be unaiected by the functioning of the other systems since the pressure of oil at the modulating valve 14 is independent of that delivered by the pump 20 and thus independent of pressures in other systems connected in parallel.

A temperature gauge 39 may be connected in the line 26 between the pressure reducing valve 36 and the modulating valve 14 to indicate the temperature of oil passing through this line.

In order to provide for the circulation of a heated quantity of oil during tiring and during shut-down to eliminate the danger of extremely viscous oils clogging thelines, a by-pass or recirculation line 41 leads from the modulating valve 14 to the return line 24 which is connected to tank. An oriiiced gate valve 42 is provided in the line 41 and is normally maintained closed so that anorifice in the gate is effective to restrict the ow of oil'through the line 41 to a volume less than the capacity ofthe heater 25. The volume of ow through the oriticed gate valve 42 is maintained at a constant volume by a back pressure valve 43 connected in the line 41 between the valve 42 and the return line 24. Pressure in the line 41 between the oriced valve 42 and the back pressure valve 43 may be read on a pressure gauge 44. The back pressure valve 43 may be manually adjusted to control the flow of oil through the orificed gate valve 42. Thus, for any one setting of the pressure reducing valve 36 and the back pressure valve 43, the volume of flow through the oriced gate valve 42, will remain constant regardless of the volume of flow passing through the modulating valve 14. Thus the volume of heated oil which is recirculated through the line 41 to the tank and back through the pump 20 may be maintained at a constant volume during shut-down of the burner, and during firing of the burner, regardless of whether the burner is being tired at a high fire rate or a low tire rate. It will be understood that the passage of oil through the modulating valve 14 to the line 41 is not subjected to the modulating effect of the valve 14.

An oil temperature interlock 45 may be provided in the recirculation line 41 to prevent opening of the solenoid control valve 16 to deliver oil to the burner nozzle 10 until the oil has reached a suitable elevated temperature on initiating operation after extended periods of shut-down.

In operation, the quantity of oil flowing through the heater 25 at any one time is determined by the burner tiring rate plus the amount of hot return oil recirculated through the line 41. The burner firing rate is determined by the demand at the burner nozzle 10, and the quantity of hot oil returned to tank is determined by the pressure settings on the valves 36 and 43 as described above. Thus, let it be assumed that under mild weather conditions, 15 gallons per hour would be a suitable volume of heated oil to recirculate through the line 41. This oil is effective to elevate the temperature of all the oil in the supply tank so as to permit its flowing to the pump 20 and from the pump to the heater 25. Also, assuming a low fire burning rate of 15 gallons per hour, the total volume of oil passing through the heater 25 would be 30 gallons per hour. Assuming a high tire burning rate of 45 gallons per hour at the burner nozzle 10, the total ow through the heater 25 would be 60 gallons per hour. When the fire is out, 15 gallons per hourl is still permitted to flow through the system so that oil at the modulating valve 14 is always hot and the burner is ready to light at any time. If extremely cold weather conditions warrant, the amount of recirculated heated oil "nay be increased to 30 gallons per hour for example, reducing the pressure on the gauge 44 by adjustment if the back pressure valve 43. On the other hand, if gconditions warrant, the pressure on gauge 44 may be increased to a point where no pressure drop occurs across the orice, and the pressure on gauge 44 is the same as that on gauge 39. Under these conditions, no hot return oil would be recirculated to tank.

Normally, heated oil is circulated through the system only during tiring and during temporary burner shutdowns. Thus, if the burner has been shut down for an extended period of time a problem is encountered in establishing the initial flow of heated oil through the system. To this end, a by-pass line 47 is provided in the system, connecting the line 26 and the line 41, and by-passing the pressure reducingvalve 36, the modulating valve 14, the orifices gate yvalve 42 and the back pressure valve 43. A normally closed by-pass valve 48 is provided in the line 47.

If the burner has not been red for an extended period of time and the system is full of cold oil, the following procedure may be utilized in establishing a flow of heated oil. The pump 20 is started. When a'pressure reading is obtained on the gauge 37, the heater 25-is turned on. After a short period of time, say ive minutes `for example, if no temperature rise is noted on the gauge 39, the by-pass valve 48 is opened. Before opening the valve 48, oil will not ow through the line 41 to the return line 24 because the pressure in the return line 24 from the relief valve 23 is higher than that in the line 41. Opening the by-pass valve 48 puts the full pressure of oil from the heater 25 in the line 47, and heated oil must move through the line 47, and through the line 24 to the supply tank, thus reducing the pressuredropdin the return line to the tank. After heated o il |has irowed through the line 47v for a vshort period S of time, say tive minutes for example, the oriced gate valve 42 is opened. This valve is left open until a temperature rise is noted on the temperature gauge 39; then the gate valve 42 is closed. Now, when the oil temperature reaches its proper value as determined by the oil temperature interlock 45, the valve 16 will be opened automatically and the burner is ready to light, since it was unnecessary to change any control valve settings.

While the viscosity of certain oils is such that they cannot be pumped under temperatures normally encountered, as described above, certain other oils may be sufficiently tluid that they can be pumped at tem peratures normally encountered. Also, while the latter oils still may require heating to obtain proper atornization for combustion, they may be properly atomized at` a much lower temperature than the more viscous oils. These characteristics of the more fluid oils permit certain economies over the system described above. For example, it may be unnecessary to return any heated oil to the supply tank while the burner is firing, or to circulate any heated oil while the burner is off. Also, since these oils may be properly atomized at lower temperatures, the capacity of the heater may be reduced. Accordingly, changes may be made in the system described for the purposes of accommodating changed conditions.

I claim:

'1. In a system for supplying viscous oil to'a burner nozzle, a pump, an oil supply line for conducting oil from the pump to the burner nozzle, a modulating valve in the oil supply line between the pump and the burner nozzle for regulating the ow of oil to the burner nozzle, a pressure-relief valve in the oil supply line between the pump and the modulating valve, a return line connecting the pressure-relief valve to the source, 'a heater intermediate the pressure-relief valve and the modulating valve for elevating the temperature of oil pumped to the modulating valve, a pressure-reducing valve in the oil supply line between the heater and the modulating valve for reducing oil pressure at the modulating valve to a predetermined value, a recirculation line leading from the modulating valve to the return line, an oriticedgate valve in the recirculation line for limiting the tlow of heated oil through the bypass line to a volume less than the capacity of the heater, a manually adjustable back-pressure valve in the recirculation line intermediate the orifced-gate valve and the return line for regulating the pressure drop across the orifice so as to vary the volume of oil recirculated to the source,

a bypass line connected to the oil supply line and the recirculation line bypassing the pressure-reducing valve,

the modulating valve, the oriced-gate valve and the backpressure valve, and a manually controllable bypass valve in the bypass line effective when opened to subject the recirculation line to the full pressure of the pump to estab lish circulation on initiating operation after extended periods of shutdown.

2. An oil tired burner system, comprising, a pump for supplying oil under pressure from `a storage tank to the system, anoil supply line for conducting oil from the pump to a burner, control valve means in the oil supply line between the pump and the burner for regulating the ow of oil to the burner, a pressure relief line connected to the oil supply line between the pump and the control valve means and leading to the tank at the upstream side of the pump, a pressure relief valve in the pressure relief line, a heater interposed in the oil supply line intermediate the pressure relief line and the control valve means having a predetermined capacity for raising the temperature of the oil, a pressure reducing valve in the oil supply line between the heater and the control valve means for reducing oil pressure to a predetermined value at the control valve means, an oil recirculation line leading from the control valve means to the tank at the upstream side of said pump, .a restrictive oriice in the recirculation line for limiting the ow of heated oil through the recirculation line to the tank to a volume less than the capacity of the heater, and a back pressure valve in the recirculation line between the orifice and the tank for maintaining a constant pressure drop across the oriiice to provide a constant ow of heated oil recirculated to the source, said back pressure valve being adjustable to vary the pressure drop across the orifice to thereby vary the volume of recirculated oil between a predetermined value approaching zero and a greater predetermined value less than the capacity of the heater.

3. An oil tired burner system as `detlined in claim 2, including gauge means in the recirculation line for indicating the pressure drop across the on'ce to enable a determination of the volume of heated oil recirculated to the tank.

References Cited in the tile of this patent UNITED STATES PATENTS 1,654,614 smith Jan. 3, 192s 1,681,663 Farckney Aug. 21, 1928 1,824,952 Graham et a1. sept. 29, 1931 2,334,679 Mason et al. Nov. 16, 1943 2,368,164 Schumann et a1. Jan. 3o, 1945 FOREIGN PATENTS 198,311 Switzerland Sept. 1, 193s 

